The German automaker Volkswagen is promising that it will no longer support the use of animals in testing the effects of diesel exhaust, as the company tries to move past an emissions-cheating scandal in which it was found to have helped finance experiments on monkeys.
The pledge was made in a letter to the German branch of the animal rights group People for the Ethical Treatment of Animals. It is part of a push by Volkswagen, Europe's biggest car manufacturer, to cope with the toll of a scheme that has resulted in tens of billions of dollars in settlements and fines, the dismissal of successive chief executives and the arrest and imprisonment of top company officials.
The cheating, which involved Volkswagen's illegally rigging the software on millions of vehicles to make it seem as if they complied with pollution standards, has also caused a major shift in the public's perception of diesel. The fuel had been promoted as an environmentally friendly alternative to gasoline, but governments in Europe and elsewhere are increasingly restricting its use.
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Volkswagen's reputation was further tarnished by the revelation that it and other German automakers had financed research on the health effects of diesel exhaust that involved spewing it at 10 macaque monkeys in airtight chambers. The disclosure touched off an uproar, piling pressure on Volkswagen and the other companies.
Volkswagen said in its letter to PETA, which was released on Monday, that it would abandon the practice.
Herbert Diess, the carmaker's chief executive, questioned the ethical decision to conduct experiments on primates, even though he maintained that the studies, which were carried out in the United States, did not violate local laws.
"Research projects and studies must always be balanced with consideration of ethical and moral questions," Mr. Diess wrote in the letter. "Volkswagen explicitly distances itself from all forms of animal abuse. In the future, we will rule out all testing on animals, as long as there are no pressing — such as legal — reasons that would make this necessary."
He added that the company would add the new standard to its code of conduct this year and that it would apply to all 12 of Volkswagen's brands and all 640,000 of its employees.
The move is the latest measure Volkswagen has taken to repair its reputation since Mr. Diess was appointed chief executive in April. He acknowledged in a speech soon afterward that the carmaker had "to become more honest, more open, more truthful."
PETA welcomed the latest development.
"Volkswagen did the right thing in pledging to no longer conduct tests on animals, which are irrelevant to human health and not required by law," said Kathy Guillermo, a senior vice president at the group. "PETA is calling on other carmakers that still test on animals to follow suit and embrace modern and humane, animal-free research methods instead."
For Volkswagen, the fallout from the diesel-cheating episode has yet to abate. Last month, a former chief executive of the company, Martin Winterkorn, was charged with conspiracy over the emissions rigging. The carmaker also faces a lawsuit by shareholders that could add around $10 billion to the huge cost the company has already incurred.
Volkswagen has pleaded guilty in the United States to charges related to the scheme, admitting that it illegally sold nearly 600,000 vehicles equipped with so-called defeat devices. It has paid more than $25 billion in fines and civil damages. Two executives have been sentenced to prison, and American authorities have brought charges against several others.
A Volkswagen spokesman did not immediately respond to a request for comment.